Thanks for the feedback, guys!
Stuart, here's more info:
First, I shoot digital only so I am always capturing in color (you can't make a raw file b/w in the camera anyway). Forget the in-camera black and white options.
A color digital capture has much more potential for b/w conversion that you'd have using b/w film.
For each image, I choose what gray tone a given color will become.
For example, in the Zebra Canyon shot, the sandstone was several different shades ranging from orange to purple. I made the purples darker in the grayscale conversion, and the oranges lighter.
In Lightroom (I love LRs b/w conversion capabilities):
1. Keep the image in color
2. HSL > Saturation: lower the Saturation for all colors to -100.
3. HSL > Luminance - have fun.
4. Try changes to White Balance at this point, too.
Certain compositions lend themselves much better to b/w conversion than others. I previsualized each image as b/w when I captured it.
Scenes with wide dynamic range, lots of fine detail and, and somewhat ironically, lots of color variation, make the best candidates for b/w.
Consider that in our normal eyesight, color is a critical component of recognition. The fact that a stop sign is red helps us "see" it better.
In b/w photography, the removal of the color component of seeing means that the visual cues (shapes, lines, light/shadow etc.) have to come from tone contrast alone.
Also, b/w photography is much more dependent on quality of light and its appropriateness to the subject than is color photography.
There's lots to be said for developing the ability to "see in black and white"; I can't. I just recognize compositions that would be stronger without color, and fiddle with the gray tones in Lightroom.